JP3309138B2 - Measuring method of rotation center position of rotating body by measuring displacement of three points and measuring device therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can measure the position of the center of rotation of various rotating bodies, and is particularly suitable for measuring the position of the center of rotation of a rotating body in machining such as tools and workpieces. The present invention relates to a method for measuring the position of the center of rotation of a rotating body by measuring displacements at three points and a measuring device therefor.

[0002]

2. Description of the Related Art Measuring the position of the center of rotation of a rotating body is required in various fields. In particular, the position of the center of rotation of a rotating shaft fluctuates due to the structure of the shaft and bearing, the number of rotations, external force acting on the shaft, and the like. Therefore, the measurement is difficult, and various techniques have been developed for that purpose. Above all, the machine tool spindle performs machining while holding and rotating tools or workpieces with various shapes and weights, so the above fluctuations are directly related to machining results such as dimensional shape, machining surface shape, etc. Will have a significant effect. Therefore, it is required to design the spindle system such that the axis center fluctuation is acceptable for the required machining accuracy.

For example, in an ultra-precision processing machine that requires a processing accuracy of 0.01 μm, it is necessary to suppress the fluctuation of the rotation center position to the same order of 0.01 μm or less. In precision turning, it is also an important technical issue to match the height of the tool edge with the position of the rotation center with high accuracy, but in order to address these issues, first, In addition, it is necessary to establish a method for detecting the rotation center position of the spindle during machining rotation with high accuracy on the order of submicron or nanometer.

[0004] In order to solve the above-mentioned problems, the present inventors have been conducting research on this related technology for a long time, and have found that the patent No. 20
No. 71913 and Japanese Patent No. 2090587. Japanese Patent No. 2071913 entitled "Method and Apparatus for Detecting Rotation Center Position of Rotation Shaft" is disclosed in FIG.
As shown in the figure, a high-precision steel ball is attached to the end of the rotation axis (Z) axis, and the displacement amount caused by the displacement (e) between the rotation center (O) and the steel ball center (A) is A rotation synchronization component (z) is detected. At this time, measurement is performed while scanning the non-contact displacement meter in the Y-axis direction and the X-axis direction (a direction perpendicular to the drawing), and a position where z is minimum, that is, a rotation center position (O) is obtained.

[0005] Also, in the above-mentioned Japanese Patent No. 2090587, "a method and an apparatus for automatically detecting the rotation center position using a flat substrate and three sensors" are described in which a highly accurate flat substrate is slightly inclined with respect to the Z axis by a goniometer at the shaft end. Attach, and three non-contact displacement meters are arranged at the vertices of an equilateral triangle in the XY plane facing this flat substrate. A rotation synchronization component is extracted from a relative displacement signal between the rotating flat substrate and the displacement meter, and a phase difference between each of the three synchronization components by the adjacent displacement meter is detected. As a result, the phase difference is defined as the circumferential angle, and the center position of two adjacent displacement meters (2
Three vertices) can be drawn. The coordinates of the intersection of these three circles coincide with the rotation center position. This circle and its intersection point are obtained by calculation.

[0006]

The above-mentioned Patent No. 20719 is described.
In the invention of No. 13, when scanning the non-contact displacement meter, at a constant interval (p) over a relatively long distance,
It is necessary to detect the rotation synchronization component (z) by performing sampling and averaging several times, and to move the displacement meter while performing the storage operation. Since this is performed for both the X and Y axes, the time required for one measurement becomes longer.

[0007] Strictly speaking, the position of the center of rotation of the rotating body constantly fluctuates, so that the measurement time is desirably as short as possible. On the other hand, in order to increase the measurement accuracy, it is better that the measurement interval (p) is short, but this increases the measurement time. As described above, this method has a disadvantage that the measurement accuracy and the measurement time are in an opposite relationship.

In the invention of Japanese Patent No. 2090587, mounting of a high-precision flat substrate using a flat mirror made of optical glass or soft metal usually poses a serious problem. That is, since the mounting object is a rotating body, it is necessary to securely mount the rotating body so that the loosening does not occur during rotation. However, in general, the flatness of a flat substrate is reduced by an external force acting upon mounting. The effect becomes greater as the precision of the substrate becomes higher. At present, a technology for mounting the flat substrate on the rotating body while maintaining the flatness of the flat substrate, and a mounting technology that is not affected by the centrifugal force acting during rotation have not been established. As described above, the mounting technology of the flat substrate serving as a reference for measurement has not been established and is under development.

Therefore, according to the present invention, measurement can be performed in a short time by a simple operation, and the rotation center position can be measured at a high speed with a high accuracy without using a flat substrate and by a simple calculation. An object of the present invention is to provide a method of measuring the position of the center of rotation of a rotating body by measuring the displacement of a point and a measuring device therefor.

[0010]

According to the present invention, in order to solve the above-mentioned problems, according to the first aspect of the present invention, a sphere is attached to the tip of a rotation axis to be measured, and the sphere is located at the apex of a triangle in one plane. And a signal component z synchronized with rotation included in the relative distance in the axial direction between the sphere rotating at a specific rotation speed and the non-contact type displacement meter, wherein the non-contact type displacement meters are arranged to face the sphere. Then, the proportional constant α between the rotational center position and the distance y between the non-contact displacement meter is obtained, and then the three displacement meters are brought closer to the sphere rotating at the target number of revolutions to rotate within the relative distance in the axial direction. The synchronous components z are simultaneously detected, and the distance y between the three non-contact displacement gauges and the rotational center position is calculated from the three z values and the proportionality constant α. Find the equation of three circles centered on the vertex position, and find the intersection of each circle Measuring the center of rotation of the rotating shaft is a method of measuring the position of the center of rotation of the rotating body by measuring the displacement at three points.

The invention according to claim 2 is characterized in that a sphere fixed to the tip of the rotation axis to be measured and a sphere located at the apex of a triangle in one plane and opposed to the sphere are arranged on a movable base.
A non-contact displacement meter, a rotation synchronization component detection device that detects a rotation synchronization component based on a signal from the displacement meter, and an arithmetic device, and the sphere rotating at a specific rotation speed and the non-contact displacement meter Means for calculating a proportional component α between a signal component z synchronized with rotation included in the relative distance in the axial direction and a distance y between the center of rotation and the non-contact displacement meter, and the sphere rotating at the rotation speed to be measured. Means for simultaneously detecting the rotation synchronizing component z within the relative distance in the axial direction by bringing the three displacement gauges closer to each other, and three non-contact displacement gauges based on the three z values and the proportionality constant α. Means for calculating the distance y from the center position, means for calculating the equation of three circles with each y as a radius and each vertex position of the triangle as the center, and measuring the rotation center of the rotation axis from the intersection of each circle And a means for performing This is a device for measuring the rotation center position of the rotating body by displacement measurement.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing a specific embodiment of the present invention, a principle of measuring a rotation center position of a rotating body according to the present invention will be described. The present invention relates to the twentieth patent.
A high-precision sphere such as a steel ball is attached to the shaft end in the same manner as in the technique of No. 71913. Then, the non-contact displacement meter arranges three non-contact displacement meters at the positions of the vertices of an equilateral triangle in the XY plane facing the sphere as in the above-mentioned Japanese Patent No. 2090587. As described in the above-mentioned Japanese Patent No. 2071913, the rotation synchronization component z may be regarded as being proportional to the value of the position y of the non-contact displacement meter. If this proportional relationship is measured in advance and the proportional constant α is determined in advance, the value of y can be calculated by measuring z. The present invention
This relationship is used.

First, as shown in FIG. 2, values of rotation synchronous components Z _S , Z _T , and Z _U at three points are measured by a non-contact displacement meter arranged at the vertices (S, T, U) of an equilateral triangle. Are simultaneously detected. Next, y values y _S , y _T , and y _U of each point are calculated from the z values of the three points using the above-described proportional constant α. And FIG.
As shown in (1), an equation of a circle having each vertex position as a center point and y as a radius is obtained. For example, a circle radius is _{y S} around the point S (a, b) can be represented as ^{(x-a) 2 + (} y-b) 2 = y S 2 (1). The three circles have one intersection, and their positions coincide with the rotation center position (O). Therefore,
The present invention measures the rotation center position of the rotating body by obtaining the intersection of the three circles as described above.

A specific embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a sphere 2 is attached to the end of a rotating shaft 1 and three non-contact displacement meters 3, 4, and 5 having the same performance are positioned at the apex positions (S, T, U) of an equilateral triangle. And mounted on the fine movement stage 6. The output of each displacement meter is input to a rotation synchronization component detection device 7 composed of a filter, and after detecting the rotation synchronization component, is input to a calculation device 9 of a personal computer 8 and performs calculation based on the above equation. The rotation center position is obtained and output to a rotation center position output display device 10 for displaying the rotation center position.

In actual measurement, first, the rotating shaft 1 on which the sphere 2 is mounted is rotated at a specific number of revolutions, and the non-contact displacement meters 3, 4, and 5 are moved by the fine movement stage 6 with respect to the sphere 2. . At this time, as in the case shown in FIG. 4, while moving the displacement meter in the Y-axis direction, the movement amount y of the displacement meter and the change amount of the rotation synchronization component z of any one displacement meter are measured. The proportional constant α is obtained from the relationship between y and z.

Next, the sphere rotating at the target rotation speed is measured.
Then, the three displacement meters are brought closer by the fine movement stage 6 and turned.
Inversion synchronization component Z_S, Z_T, Z_UAre detected simultaneously (see Fig. 2).
See). This is input to the computing device of the personal computer
And using the proportionality constant α _S, Y_T, Y_UConvert to
You. This allows the coordinates of S, T, and U in the XY plane to be
Y as the center point_S, Y_T, Y_UEquation of a circle with radius
(1) is calculated, and its intersection is obtained (see FIG. 3). this
Of the rotation center position O (x, y) obtained in the manner described above.
Output to 10

[0017]

Since the present invention is constructed as described above, the time-consuming operation of the displacement gauge as in the prior art 1 is unnecessary, and the flat substrate as in the prior art 2 is not required. Only by simultaneously detecting the rotation synchronization component z at three points, the rotation center position at the detection time can be calculated by calculation thereafter, and highly accurate measurement can be performed. This calculation is simpler than the calculation in the above-described conventional technique 2, and the calculation speed can be increased. Therefore, the rotation center position can be measured with high speed and high accuracy.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment of the present invention.

FIG. 2 shows a rotation center position in the XY plane of the present invention;
It is explanatory drawing showing the positional relationship of a spherical body and a displacement meter, and the value of the rotation synchronous component z measured by three displacement meters.

FIG. 3 is an explanatory diagram showing that y is calculated from z in FIG. 2 and that an intersection of circles having radii of y _S , y _T , and y _U centering on the positions of three displacement meters coincides with the rotation center position. It is.

FIG. 4 is an enlarged plan view showing the principle of measurement according to Prior Art 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation axis 2 Sphere 3,4,5 Non-contact displacement meter 6 Fine movement stage 7 Rotation synchronous component detection device 8 Personal computer 9 Arithmetic device 10 Rotation center position output display device

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 21/00

Claims (2)

(57) [Claims] 1. A sphere is attached to the tip of a rotation axis to be measured, and three non-contact type displacement meters located at the vertices of a triangle in one plane are arranged to face the sphere and rotate at a specific rotation speed. Obtain a signal component z synchronized with rotation included in an axial relative distance between the sphere and the non-contact type displacement meter, and a proportional constant α between a rotation center position and a distance y between the non-contact type displacement meter, and then measure The three displacement meters are brought closer to the sphere rotating at the target rotation speed, and the rotation synchronization component z within the relative distance in the axial direction is obtained.
Are simultaneously detected, and the distance y between the three non-contact displacement gauges and the rotation center position is calculated from the three z values and the proportionality constant α, and each vertex position of the triangle is determined using each y as a radius. A method of measuring a rotation center position of a rotating body by measuring displacements of three points, wherein an equation of three circles having a center is obtained, and a rotation center of a rotation axis is measured from an intersection of each circle. 2. A sphere fixed to a tip of a rotation axis to be measured,
Three non-contact type displacement meters located on a movable table facing the sphere at the vertices of a triangle in one plane, and a rotation synchronization component detection device for detecting a rotation synchronization component based on a signal from the displacement meter A signal component z synchronized with rotation included in an axial relative distance between the sphere rotating at a specific rotation speed and the non-contact type displacement meter, a rotation center position, and a non-contact displacement meter Means for obtaining a proportional constant α with respect to the distance y between the two, and means for simultaneously detecting the rotation synchronization component z within the relative distance in the axial direction by bringing the three displacement meters close to the sphere rotating at the target rotational speed. Means for calculating the distance y between the three non-contact displacement meters and the rotation center position from the three values of z and the proportionality constant α, and setting each y as a radius to each vertex position of the triangle as a center. Means to find the equations of the three circles Means for measuring the center of rotation of the rotating shaft from the intersection of the circles.